High time resolution TOF for SoLID Wang Yi Department of Engineering Physics, Tsinghua University Outline: Conceptual design of SoLID-TOF Performance and aging Structure of narrow-gap MRPC Cosmic and beam test Conclusions

Motivation JLab 6 GeV: precision measurements high luminosity (1039) but small acceptance (HRS/HMS: < 10 msr) or large acceptance but low luminosity (CLAS6: 1034) JLab 12 GeV upgrade opens up a window of opportunities (DIS, SIDIS, Deep Exclusive Processes) to study valence quark (3-d) structure of the nucleon and other high impact physics (PVDIS, J/y, …) High precision in multi-dimension or rare processes requires very high statistics  large acceptance and high luminosity CLAS12: luminosity upgrade (one order of magnitude) to 1035 To fully exploit the potential of 12 GeV, taking advantage of the latest technical (detectors, DAQ, simulations, …) development SoLID: large acceptance detector can handle 1037 luminosity (no baffles) 1039 with baffles

Overview of SoLID Full exploitation of JLab 12 GeV Upgrade Solenoidal Large Intensity Device Full exploitation of JLab 12 GeV Upgrade  A Large Acceptance Detector AND Can Handle High Luminosity (1037-1039) Take advantage of latest development in detectors , data acquisitions and simulations Reach ultimate precision for SIDIS (TMDs), PVDIS in high-x region and threshold J/y 5 highly rated experiments approved (+3) Three SIDIS experiments, one PVDIS, one J/y production (+ three run group experiments) Strong collaboration (250+ collaborators from 70+ institutes, 13 countries) Significant international contributions (Chinese collaboration)

Main requirements for TOF The MRPC is developed for the TOF of SoLID Main Requirements for TOF: /k separation up to 2.5GeV/c Time resolution < 100ps Rate capability > 10kHz/cm² To separate very few K from , we require the TOF time resolution as good as possible. We have to improve the time resolution to about 20ps.

Conceptual design of SOLID-TOF MRPC TOF wall we designed contain 150 MRPC modules in total, with 50 gas boxes and 3 counters in each box, covering the area of 10m². MRPC1 MRPC2 MRPC3 100cm 16cmm 28cm Total channel ~3600

Introduction of MRPC Read out Insulator Carbon Resistive plate MRPC is made of thin glass, large area and cheap The inner glasses are floating, take and keep correct voltage by electrostatics. it is transparent to fast signals Thin gap->good timing Multi-gap-> high efficiency Standard parameters: Resistivity of glass: ~1012 Ω.cm Time resolution <100ps Efficiency >95% Dark current: a few nA Noise <1Hz/cm2 Application in nuclear physics experiments Application in industry（Muon tomography) Application in medicine（TOF-PET） 6 6

Performance of low resistive glass Dimension Bulk resistivity Standard thickness Thickness uniformity Surface roughness Dielectric constant DC measurement 33 x27.6cm2 ~1010Ωcm 0.7, 1.1mm 20μm <10nm 7.5 - 9.5 Ohmic behavior stable up to 1C/cm2 7

Glass mass production The roughcast of glass Continuous annealing Continuous melting Continuous pouring

A MRPC prototype for SoLID-TOF Volume resistivity: ~1010.cm 363mm 219mm 171mm 25mm Material dimensions Length/mm Width/mm Thickness/mm Gas gap - 0.25×10 Inner glass 320 130-171 0.7 Outer glass 330 138-182 1.1 Mylar 335 153-198 0.18 Inner PCB 350 182-228 1.6 Outer PCB 172-218 0.8 Honeycomb 6

Beam test @ Hall A High Energy e- Shield Target PMT1 PMT3 Target PMT0 PMT2 PMT4 Top View The diagram of DAQ system Target Test setup

Rate Performance Wan Yi. A MRPC prototype for SOLID-TOF in Jlab. Voltage: 6800V Flux:11kHz/cm² Efficiency:~95% Time Resolution: 78ps Flux:16kHz/cm² Efficiency:~95% Time Resolution: 82ps Wan Yi. A MRPC prototype for SOLID-TOF in Jlab. 2013_JINST_8_P03003

Aging test of low resistive glass This glass was applied with 1000V for about 32days, integrated charge: 1 C/cm2 --roughly corresponding to the CBM life-time over 5 years operation at the maximum particle rate. Glass specifications: 12

Online irradiation test Hign rate MRPC X-ray Generator 130cm 60cm This is online test system. The efficiency and time resolution can be obtained by cosmic ray while irradiated by X-rays. 0.1C/cm2 charge is accumulated in 35 days. 13

Performance Vs Dosage ~500 events/5days More events ->Better statistics 14

TOF electronics Fast preamplifier： Ninos (TOT) (ALICE) Padi (TOT) (GSI) CAD (TOT) (Tsinghua) Low time jitter faster FEE TDC HPTDC (ALICE, 25ps/ch) GET4 (GSI, 25ps/ch) FPGA TDC (GSI and other) Pulse wave form digitizer DAQ

TOF readout chain with PADI and GET4 CLK MRPC Preamplifier & Discriminator Preamplifier & Discriminator Time to Digital Converter ROC Time to Digital Converter ROC DCB MRPC

Intrinsic resolution of 10gap-MRPC Differential FEE TDC START Time jitter of HPTDC 25ps NINOs ASIC+Interface card 24ps MRPC resolution tested 40ps So the intrinsic resolution of MRPC is:

Resolution of 24 x140m MRPC Fast wave form digitizer 30-> 5ps Low time jitter fast FEE 24-> 5ps MRPC intrinsic 20-> 13ps Time resolution of TOF: 18

PID and time resolution @ 1m distance Distance Pion-Kaon Separation Kaon-Proton Separation σtot=100 ps 1m σtot=10 ps 3m Momentum reach of TOF PID reaches interesting levels if one can achieve ~ 10 ps TOF Positives Compact (10-15 cm of space needed), allowing more room for, e.g., RICH More clean PID Can contribute to e/h identification using TPC dE/dx TOF Negatives Start counter?

Structure of high time MRPC Item dimension/mm Honeycomb 90×265×7.5 Outer PCB 120×298×0.6 Middle PCB1 120×298×1.2 Middle PCB2 120×328×1.2 Strip length 268 Strip width 7 Mylar 90×268×0.25 Glass 80×258×0.5 Carbon 72×250 Gas gap width 0.104 Number of gas gap 32 Honey comb plate PCB Mylar Carbon electrode Glass

Test equipment Fast amplifier Gas box DRS4-V5 chip 16 channels Waveform Digitizer DT5742 DRS4-V5 chip 16 channels 12bit 5GS/s 5 points for leading edge of MRPC

Cosmic test Gas Mixture : “Freon” (R134a) 90% : Iso 5% : SF6 5%

Test results Efficiency HV=5.5kV 98.37% 99.10% Efficiency of MRPC1 Charge Efficiency of MRPC1 Efficiency of MRPC2 98.37% 99.10% Charge

Time resolution σ =89.92ps Time difference of two MRPC Walk correction

Beam Test at IHEP Trigger Particle e+, e-,+,-,p momentum e 200MeV/c~1.3GeV/c  400MeV/c~900MeV/c p 500MeV/c~1GeV/c rate 10~20Hz Trigger S C 2 1 M W P e , p 5 c m 6 MRPC

Signal selection P Count  Time Time

Time resolution Difference between time of two MRPC: Δt = t2 – t1= 52ps σt = Δt/√2 = 37 ps Only protons are used Used a “Leading Edge Discriminator technique” in software from waveform, slewing correction Wings manily due to noise, cross-talk, or something else? We believe best published result is 20 ps Nucl.Instrum.Meth. A594 (2008) 39-43 Nucl.Instrum.Meth. A629 (2011) 106-110

Conclusions A SoLID-TOF MRPC prototype is developed, its time resolution is 75ps, rate capability reach 16kHz/cm2. MRPC intrinsic resolution can reach 13ps. Fast FEE and high band width wave form digitizer has to be used to improve TOF resolution -> 15ps. Very narrow-gap MRPC were designed and tested, its efficiency can reach 98% and time resolution around 37ps. More detailed research should be done to improve time resolution.

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